The Social Brain

Dolphins, known as one of the most intelligent animals, seen off Montauk, New York. Credit: Carl Safina

Why the social brain is the most intelligent brain

Dolphins and humans have not shared a common ancestor for tens of millions of years. Yet for all the seeming estrangement of lives lived in liquid, when they see us they often come to play, and we can recognize in those eyes that someone very special is home. “There is someone in there. It’s not a human, but it is a someone,” says Diana Reiss.

Different species’ brains emphasize different abilities. The nerves and brain structure for detecting and analyzing scent is an important part of a dog’s brain but essentially nonexistent in a whale’s.

Meanwhile, a sperm whale’s brain devotes enormous resources to creating, detecting, and analyzing sound. Sperm whales’ brains are larger than blue whales’, though blue whales’ bodies are twice as big. What does a sperm whale do with its singular brain? It sets courses for long migrations and keeps track of family and friends over decades, and across thousands of miles of travel. It prepares for dives deeper than a mile; manages the pumping, distribution, and shunting of blood and oxygen while the whale stops breathing for up to two hours; and controls the tracking and muscle coordination needed while hunting squid the size of your nightmares in total darkness.

If you’re going to have a larger, denser brain, you’re going to have to pay to run it. And brains are real energy hogs. At just about 2 percent of our body weight, ours costs nearly 20 percent of our body’s energy budget (that’s why mere thinking can be so tiring).